1. Field of the Invention
This invention relates generally to a device for the automatic cleaning of swimming pools, and more specifically to an improved and efficient suction-type automatic swimming pool cleaner.
2. Description of the Prior Art
Prior art has shown that a swimming pool may be cleaned automatically by a device using a cleaning head which engages the pool surfaces to be cleaned and is connected to one or a pair of tubes (either parallel or non-parallel) with a valve mechanism that interrupts the flow of pool water through the cleaning device by either periodically interrupting the constant flow of water through the single tube, or alternately delivering water through either of the pair of tubes. These suction type automatic swimming pool cleaners are typically powered by the flow of water flowing from the pool through the cleaning head, past a flapper valve, through the tube (or tubes), through a flexible hose normally associated with suction cleaners, and finally drawn into the suction side of the pool's filter pump.
The prior art is most notably represented by Hofmann U.S. Pat. No. 4,208,752 (which is manufactured and sold under the Barracuda trademark) and Chauvier U.S. Pat. No. 4,023,227 (which is manufactured and sold under the Kreepy Krauly trademark). Each of these automatic swimming pool cleaners consists of a cleaning head which is made up of a bottom opening in a plastic base which admits pool water and the debris such as dirt and leaves. This head has an elastomer disc about it which surrounds the head and increases the collecting area, and further acts as a stabilizer for the pool cleaner assembly. As the pool water is drawn up through the head it passes through a restricting orifice, offset from the longitudinal axis of the flapper valve, which is necessary to get the unpinned (free-floating) flapper valve to cycle or startup. The flapper valve cycles and as it does, it interrupts the steady suction flow to the pool's filter pump. This on-off or flow shift, depending upon the device, is amplified by the impact tube or tubes and causes a vibratory force sufficient to move the cleaner about the pools surfaces in a random fashion.
However, the offset restricting orifice, while necessary to initiate the flapper valve reciprocation, significantly limits the size of the debris that can be collected by the cleaner. In addition, debris often becomes trapped in the restricting orifice, causing system shutdown and requiring frequent cleanouts. Furthermore, the hydraulic restriction created by the orifice causes an increased electrical load on the pool pump, thereby shortening the life of the system.